At present, a flat-panel display has widely been popularized as various monitors for a personal computer and the like and as a display device for a cellular phone, and so on. In the future, the flat-panel display is expected to follow popularization more and more, such as development in use for big-screen television.
A most popular flat-panel display is a liquid crystal display. As a color display method for the liquid crystal display, one called a micro-color filter method has been used widely.
Further, in recent years, some display devices, other than the liquid crystal display, excellent in viewability have been reported as an electronic paper display. Most of these devices are intended to realize bright display without using a polarization plate. However, even in such display devices, bright display is realized with respect to monochromatic display but with respect to color display, they are required to employ micro-color filter of three primary colors of red (R), green (G) and blue (B), similarly as in the liquid crystal display. As a result, in the present circumstances, the color display has not been realized as yet with a brightness comparable to that of paper.
The micro-color filter method effects full-color display by constituting one unit pixel with at least three pixels and providing the three pixels with color filters of three primary colors of red (R), green (G), and blue (B), respectively, thus having an advantage of readily realizing a high color-reproducing performance.
On the other hand, as a disadvantage of the micro-color filter method, a transmittance is ⅓ of a monochromatic display method, so that a light utilization efficiency is low.
This low light utilization efficiency leads to a high power consumption of a back light or a front light in a transmission-type liquid crystal display apparatus having the back light or a reflection-type liquid crystal display apparatus having the front light.
As a method in place of the micro-color filter method, U.S. Pat. No. 6,154,191 has proposed a full-color display method (field-sequential color (FSC) method) wherein a time-division color mixing effect by switching images of the three primary colors at high speed is utilized. The FSC method is not required to be provided with a color filter, so that it has the advantages of a low cost and a high light utilisation efficiency. However, the FSC method requires drive of a display device at very high speed, thus exerting a large load on a drive system. As a result, an applicable display mode is limited, so that it cannot be said that the FSC method is currently popularized sufficiently.
Incidentally, in recent years, such a transflective (semi-temperature)-type liquid crystal display apparatus (display device) that a part of an area of a display device is used as a light reflection area and another part of the area is used as a light transmission area has been widely employed in a cellular phase or a mobile data terminal. Particularly, a portable electronic apparatus is required to ensure not only a sufficient viewability in very bright eternal light because it is frequently used outdoors but also a high contrast and a good color reproducibility in a dark room. In order to meet the requirements, a transflective-type liquid crystal display has been proposed in U.S. Pat. No. 6,466,280 as a transflective-type display apparatus which is considered to meet the requirements.
The above described FSC method has been conventionally proposed in a transmission- or reflection-type display apparatus but in the future, it is desired to be applied to the above mentioned transflective display apparatus. Particularly, the FSC method capable of effecting color display both in the reflection mode and the transmission mode is useful for a display of a low-cost potable apparatus.
As described above, the transflective liquid crystal display apparatus has many advantages and has been widely used but, as described more specifically later, is required to give a cell thickness difference of two times between the light transmission area and the light reflection area, thus being accompanied with such a problem that a process load for giving the cell thickness difference within the display device. Further, the transflective-type display apparatus and has a poor light utilization efficiency compared with the transmission-type display apparatus. Accordingly, the transflective-type display apparatus is required to be improved in light utilization efficiency both in the light reflection area and the light transmission area.